How to configure Office 365 users to access Office365 Public Folders?
Once you have migrated both your Public Folders and mailboxes to Office 36,5 then you need to complete this step, to ensure that your Office 365 users can access the migrated Public Folders.
Enable the Exchange online organization to access the Office 365 Public Folders. The following PowerShell script needs to be run against your Office 365 environment:
Set-OrganizationConfig -PublicFoldersEnabled Local
Note: Read the How do I enable Office 365 users to access legacy on-premises Public Folders? article if you want to enable Office 365 users to access legacy On-Premises Public Folders.